Process for vulcanizing rubber and products obtained thereby



Patented Jan. SJ, 1328.

UNITED V STATES 1. 51.522 PATENT OFFICE.

MORRIS L. WEISS, OI NEWARK, NEW JERSEY, ASSIGNOB TO DOVAN CHEMICAL COR- IPOBATION, F YORK, N. Y., A CORPORATION OF NEW YORK.

PROCESS FOR 'VULCANIZING RUBBER AND I PBOIDUCTS OBTAINED THEREBY.

No Drawing. Application filed August 7, 1925, Serial No. 48,889. Renewed J'uly 1, 1927. i

, 'Ijhis invention relates to processes for vulcanizing rubber and similar materials and to the products obtained thereby, and is more particularly directed to acceleration of vule canization b a class of products .formed by reaction with substituted guanidines.

One of the objects of the invention is to provide a material which will eificiently accelerate vulcanization of rubber, particu- 1u larly at relatively. high temperatures; to provide a simple process for the use of the material and to produce a series of useful vulcanized rubber products.

In accordance with my invention I have found that the diphenyl guanidine reaction product with 2-6 dimercapto 3-5 diphenyl -oxy pentathiopheneand similar substances are valuableaccelerators of vulcanization.

My invention accordingly comprises a process for treating rubber which includes combining rubber with a reaction product of a substance having the general formula 0 R-o-d-m-R HS an with a basicsubstituted guanidine having an imid group as a vulcanizing ingredient and vulcanizin the rubber. R in the above formula may e either alkyl or aryl. In using the expression as a vulcanizing ingredient I mean that the reaction product is a component part of the combination or mixture which is used to effect vulcanization and which ordinarily includes sulfur and may, and preferablydoes include zinc oxide or equivalent thereof.

'tion of 790 per cent.

In carrying out the process in its preferred form I .mix preferably on the mixmg mill in the usual manner, 100 pounds of pale crepe rubber, 3 pounds of sulfur, 5 pounds of zinc oxide, 1 pound of 2-6 dimercapto 3-5 diphenyl 4-oxy pentathiophene. After milling is complete the mixture is placed in amould and heated at pounds per square inch steam pressure for minvu'lcanization has occurred. c

I have found that the rubber vulcanized utes, at the end of which time satisfactoryin this manner has a tensile strength. of

3342 pounds per square When compared with diphenyl guanidine, wh ch 1s one ofthe reacting substances from which the preferred accelerator is made, it is found that it possesses somewhat similar inch and an elongaaccelerating properties to this substance but operates at a somewhat higher temperature than diphenyl guanidine; This property insures practically com lete freedom from revulcanization or inning in milling.

en the preferred accelerator is compared with 2-6. 'dimercapto 3-5 diphenyl l-ox i i pentathiophene, it is found that it is muc stronger. than this latter substance which, it will be recognized, is one of the parent substances from which the preferred accelerator is made. I have given below a tabulation showingthe results of vulcanization employing respectively and successively, diphenyl guamdine, 2-6 dimercapto 3-5 diphenyl 4-.oxy pentathiophene, and the reaction product of diphenyl guani'dine and 2-6 dimercapto 3-5 diphenyl l-oxy pentathiophene at varying temperatures and times. 1

an min .@20 lbs/in. 4s min.@20 Ibs./in.

t rused Amara 0 Per cent Lbs/in. Per cent LbsJlnJ elong. tensile elong. tensile di 11 1 guanldine and 2-6 dimerce to 3-5 di hen '1 i-oxy pentaitiittnfifi p Y h p p y got 7 0 lira dim a to 3-5 di hen 14-0 pentafhinn me oc l phengl m anifline p y xy 950 460 935 1040 20 mm. 4o1bs./m.= so min.@40 lbs/in. 45 m1n.@40 lbsJin) so min.@40 lbs.'/in.

Per cent LbsJin. Per cent Lba/in. Per cent Lbs./ in.' Per cent Lbs./ln. along. tensile elong- =tenslle along. y tensile elong. tensile Reaction roduct of diphenyl guanidine and 2-6 l I dimerca ito 3-5 diphenyl 4-0xy pentathiophene 910 2, 487 840 2, 84B 790 3, 342 3, 727 Diphenyl mmnidine 885 2, 637 v 880 2, 945 760 3, 552 760 3, 910 2-6 dimercapto 3-5 diphenyl it-orgy pentatluophenel- 1, 030 1,120 950 1, 210 980 1, 872 960 2, 102

The compounds used in carrying out the above test were as follows;

. Pounds. Pale crepe rubber 100 Sulfur 3 Zinc oxide 5 Accelerator 1 the same as given in the preferred'example above. For example, at 40 pounds steam pressure for minutes employing six parts -zationwill occur under such conditions.

of sulfur with the ingredients remaining the same I have obtained a tensile strength of 3710 pounds per square inch as compared with 3342 pounds per square inch where a less amount of sulfur is employed.

It will be understood that the reaction product given in the preferred example may be replaced in whole or in part by other similar substances, for example, in the reaction product of diphenyl guanidine and 2-6 dimerca to 3-5 diphenyl -oxy pentathiophone, the phenyl groups of the latter substance may be replaced by alkyl or aryl groups to provide similar results upon vulcanization. The alpha and beta positions of the guanidine may also be substituted as desired. It will be observed that the preferred example given above employs zinc oxide. I

have found that zincoxide may be omitted if desired, and some acceleration of vulcani- It is preferably, however, that zinc oxide or its equivalent be present.

In preparing the reaction product men-'- tioned in the referred example, the sodlum salt of 2-6 dimercapto 3-5 diphenyl 4-oxy pentathiophene is prepared in accordance with a procedure which may be found in literature. This sodium salt is dissolved in water and is treated with a water solution of diphenyl guanidine hydrochloride. The reaction whlch occurs is as follows men OaHrNH NHCuH:

The resulting reaction product which is only slightly soluble in water is precipitated and filtered ofil. It may be recrystallized from ethyl alcohol in which it is soluble. The resulting purified product is a lemon yellow crystalline substance which has a melting point of approximately 189 C.

\ Upon heating the substance above this melting point decomposition does not occur until approximately 205 C. has been reached. The compound is thus clearly distinguished from the parent substance 2-6 dimercapto 3-5 diphenyl boxy pentathiophene which has a melting point of approximately 165 C. and which decomposes at that temperature. The'reaction product is further distinguished by the fact that it possesses substantially no mercaptan odor, Whereas 2-6 dimercapto 3-5 diphenyl -oxy pcntathiophene has a disagreeablecharacteristic mercaptnn smell.

, As many apparently Widely different embodiments of this invention may be made and a basic substituted guanidine having an imid group as a vulcanizing ingredient, and vulcanizing the rubber.

2. A process for treating rubber, which comprises combining rubber with a reaction product of 2-6 dimercapto diphenyl el-oxy pentathiophene and a disubstituted guanidine having an imid group as a vulcanizing ingredient, and vulcanizing the rubber.

3. A process for treating rubber, which comprises combining rubber with the mac tion product of 2-6 dimercapto 3-5 diphenyl 4r-oxy pentathiophene and diphenyl guanidine-having an imid group as a vulcz'inizing ingredient, and vulcanizing the rubber.

4. A process for treating rubber, which comprises combining rubber, a zinc co1npound, sulfur and the reaction product of 2-6 dimercapto 3-5 diphenyl foxy pentathiophene and diphenyl guanidinc having an imid group and vulcanizing the rubber.

5. As a. new product, a vulcanized rubber derived from rubber combined with a reaction product of a substance having the general formula and a basic substituted guanidine having an imid group as a vulcanizing ingredient.

6. Asa new product, a vulcanized rubber derived from rubber combined with a reaction product of 2-6 dimercapto 3-5 dilflll Ill) - stituted guanidin'e having an imid group. 7 As a new product, a. vulcanized rubber phenyl 4-oxy pentathiophene and a disubderived from rubber combined with the reac- 5 tion product of 2-6 dimercapto'3-5 diphenyl- 4-oxy pentathiophene and diphenyl guanidine having an imid group as a vulcanizing ingredient.

8. As a new product, a vulcanized rubber derived from rubber combined with sulfur, a 10 k compound of zinc and the reaction product of 2-6 dimercapto 3-5 diphenyl -oxy penta: thiophene and diphenyl guanidine, having an imid group, as a vulcanizing ingredient.

Signed at New York, N. Y., this 6th day of August, 1925.

MORRIS L. WEISS.

GERTZFIGATE 0F GORRECTIQN.

Patent No. 1.651522.

MORRES L. WEISS.

It is hereby certified that error appears in the abave numbered patent requiring correction as ioilows: In the heading to the printed specification, line 6, date of Renewal 01' "Juiy l, 1927;" read "May 19, 1927,"; and that the said Letters Patent should b2 read with this correction therein that the same may conform to the record of the case in the Pnien'i Office.

Signed and sealed this 21st day of February, A. D. 1928.

M. J. Moore, Seal. Acting Gommisaiumr of Patents.

Granted January 31, 1928, to 

